Idle Fuel Consumption

[WisdomWarlord]

I have a 1993 Ford F-350 with a stock 7.3l IDI engine, non-turbo. With winter here and the possibility of brutally cold weather, I'm considering not shutting the engine off for several weeks unless I need to for service. Does anyone know with reasonable certainty how much fuel my engine should consume per hour or in hours per gallon? I know that my 1989 F150 with the stock 4.9l straight 6 would consume 1 gallon per 4.5 hours. If this engine consumes that much, I'm gonna have to seriously budget in the extra fuel cost but it's better in my opinion than a - 20°f cold start. So, has anyone done the work to figure this out yet ? I'm hoping the number is closer to 10 hours per gallon

Thanks
Keith HP

 

[Silver Burner]

Can you not just plug it in to a block heater overnight or setup and actual coolant heater? Seems like it would be cheaper in the long run and not nearly as bad as running a diesel for literally weeks at a time.

 

[C.J.]

I'd vote for the block heater. I've got mine plugged into a timer that kicks it on about 2 to 3 hours before I head out the door. I'm more interested in a radiator cover to limit airflow so as to retain more heat in my engine during these cold temps while I'm bombing down the freeway and such.

 

[lindstromjd]

I think it's close to 1 gallon every 3 hours. It may be less, but that's what I was told a DT444 (powerstroke 7.3) will consume at idle.

Honestly, I don't see why you would need to run it nonstop. Just plug it in, and with a good, working block heater you won't be fighting the bitter cold. You could even plumb in a bypass heater, and get a fuel tank magnet-type heater for your fuel. Electricity is far less expensive than fuel these days.

 

[WisdomWarlord]

I have entertained the various heaters to do this and may still, but it would mean heating the batteries and remote oil filters and coolant, and possibly the fuel water seperator. That's a lot of stuff to fail and derail my objective, which is to be sure the truck is going to start when I need it no matter the weather. But, if 3 hours per gallon is a reasonable number, I'll have to rethink thus! Of course I should have been thinking of this when it was 90 out right!

 

[tanman_2006]

Get 2 magnet style heaters and slap one on the oil pan and one on the trans pan, those plus the block heater will make your truck ready to rock and roll at start up. Personally I have 2 block heaters on my 95 and get by just fine using the low voltage one, I've only plugged the high output one in twice. Otherwise I just let it idle 5-10min before heading out and take it easy on the trans until it warms enough to lock the converter.

 

[Hydro-idi]

So your plan is to run the truck in the driveway at idle and not shut it off for weeks at a time? No offense to you at all, and please do not take me wrong here, but I am not understanding the logic or reason behind this. Idling a diesel engine for an extended period of time is a sure way to wash those cylinders down...and when that happens, piston rings and/or bores are toast. When a diesel engine idles for extended periods of time at idle, the engine does not build enough heat to fully combust the fuel in cylinders. In turn, the diesel fuel will wash the lubrication off of the cylinder walls and severely wear those piston rings and scrape away the cross-hatching in the cylinders. It would make more sense to just plug in your block heater. It will keep the engine plenty warm.

 

[Kevin 007]

If one was off the grid, a Wabesto engine heater would be the option. Pricey but are they ever a neat unit!!! As for leaving it running for weeks, maybe if you were in the arctic circle and it dipped to 50 below or something, then I wouldn't hesitate. But just seems to be a waste of expensive fuel to be doing that in not horrific temps

 

[FORDF250HDXLT]

doesn't even look like you need a block heater to me.

http://www.weather.com/weather/wxclimatology/monthly/graph/USMI0230


iv never had my idi take longer than 3 seconds to start (once i repaired it's systems/tuned it.)


iv never used my block heater.
i don't even know if it works.iv never had a reason to find out.i see a decent enough looking cord,that's as far as iv gotten lol.

 

[tanman_2006]

I don't NEED mine but it sounds better being plugged in and I am testing the better mpg if plugged in theory. So far I have a slight increase.

 

[Can30Diesel]

Like was said above, diesel engines don't like extended idling, even diesel generators run quite a ways above an idle. It looks like if you do decide to run the truck at idle for weeks on end it will become very costly. . I'd just make sure your coolant is in good shape and at the right ratio and plug in the block heater. There are additives you can get for fuel that help with gelling and freezing if you have concerns about that.

 

[pedro_8149]

even here in terrace for the last two weeks it has been about -21*C over night and maybe -15 during the day i plug the block heater in all night and start it for like 5-8 mins prior to leaving and i have heat right away. i havent had any issues starting, even the one night i forgot to plug it in was the coldest night and it started like it was just running. i also dont have my rad blocked off or anything i have a billet grill that allows a lot more air in the normal and it being windy here doesnt ever affect it. i did do the high idle over ride mod so if i do leave it idleing while im doin service work on equipment in the field i bump it up to help prevent cylinder wash. but as far as im concerned letting it idle for hours on end is in no way neccasary. just my personal .02 is all.

 

[Goofyexponent]

The IDI is extremely efficient at idle. All diesel engines are. A diesel will only butrn the fuel that it NEEDS to stay running, where as a gasser will waste some fuel at idle.

HOWEVER, if you plan on leaving the engine idle for weeks on end, plan on doing oil changed at one week intervals. The fuel "washdown" into your oil will severely shorten the lifespan of teh oil.

At idle, teh engine is not hot enough and not working hard enough to burn ALL the fuel. It squeezes past the cylinder, the rings and drips down into the oil. This is why when you do an oil sample and you have a higher than usual fuel content, they will say ti idle less and check for mechanical fuel leaks at the pump, etc.

 

[Matrix37495]

The IDI is extremely efficient at idle. All diesel engines are. A diesel will only butrn the fuel that it NEEDS to stay running, where as a gasser will waste some fuel at idle.

HOWEVER, if you plan on leaving the engine idle for weeks on end, plan on doing oil changed at one week intervals. The fuel "washdown" into your oil will severely shorten the lifespan of teh oil.

At idle, teh engine is not hot enough and not working hard enough to burn ALL the fuel. It squeezes past the cylinder, the rings and drips down into the oil. This is why when you do an oil sample and you have a higher than usual fuel content, they will say ti idle less and check for mechanical fuel leaks at the pump, etc.

If he did the high idle override mod, wouldn't that help reduce some of that? Of course it would also raise the fuel comsumption...

I live in town so my truck would probably get stolen if i left it running for that long... :/

 

[PwrSmoke]

Come on... it's Detroit, not Siberia! ( : < ) Most every IDI I've ever seen, even down in Phoenix, was built with a block heater (though it may not have the cord... look at the freeze plug just forward of the starter)and it's relatively easy to install if yours is one of the few that dossn't have one. Running the truck for weeks will likely cost more than buying the block heater and, as it was said above, fuel dilution will become a big problem. Remember efficient diesel combustion depends on HEAT. The engine generates very little heat at idle so combustion temps will be low, the engine will slobber and unburned fuel will wash down the cylinder walls. Not good.

My truck has started at -15F without being plugged in. It didn't like it, but started under protest. It had strong batteries, a good winter grade oil (I use 10W30) and non-gelled fuel. Plugged in, the truck starts as good as on a warm day, no matter how cold it is, and I get defroster heat that much sooner. My truck is in the barn now for winter, but I found a temperature controlled switch that you plug into an outlet. When the temp drops to 35K (or whatever setting it's built for), power flows. I keep my small (Ford) diesel tractor plugged in most all winter with it so I know it will start for snowplowing when I need it. Could do the same with the truck if I needed it for winter.